Method and apparatus for performing access barring check

ABSTRACT

Provided are a method for a user equipment (UE) to perform access barring check in a wireless communication system, and an apparatus supporting the same. The method may include: receiving a list of barring information, wherein each of the barring information includes a barring factor and a barring time; receiving information on an access category related to barring information included in the list; performing the access barring check for the access category, based on the barring information related to the access category; and performing uplink transmission, if an access attempt is allowed for the access category.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/252,435, filed on Jan. 18, 2019, which is a continuation pursuant to35 U.S.C. § 119(e) of International Application PCT/KR2018/007142, withan international filing date of Jun. 25, 2018, which claims the benefitof U.S. Provisional Patent Applications Nos. 62/523,799, filed on Jun.23, 2017 and 62/523,786, filed on Jun. 23, 2017, the contents of whichare hereby incorporated by reference herein in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a wireless communication system, andmore particularly, to a method for a user equipment (UE) to performaccess barring check and an apparatus supporting the same.

Related Art

In order to meet the demand for wireless data traffic, which has beenincreasing since the commercialization of a fourth-generation (4G)communication system, efforts are being made to develop an improvedfifth-generation (5G) communication system or pre-5G communicationsystem. For this reason, a 5G communication system or pre-5Gcommunication system is referred to as a beyond-4G-network communicationsystem or post-long-term evolution (LTE) system.

SUMMARY OF THE INVENTION

Meanwhile, since access categories involve service type property,accesses belonging to a particular service shall be processed withhigher priority than others. For example, accesses for emergencyservices shall have higher priority than that of normal services, oraccesses for normal services may have higher priority than that ofInternet of Things (IoT) data transmissions. Meanwhile, in the NR, 64access categories are defined, and access baring check may be applied to63 access categories. If access baring parameters is defined for each ofthe access categories, signaling of a network for transmission of theaccess baring parameters may increase. Therefore, access barring checkmechanisms based on access barring information set need to be proposed.

One embodiment provides a method for performing, by a user equipment(UE), access barring check in a wireless communication system. Themethod may include: receiving a list of barring information, whereineach of the barring information includes a barring factor and a barringtime; receiving information on an access category related to barringinformation included in the list; performing the access barring checkfor the access category, based on the barring information related to theaccess category; and performing uplink transmission, if an accessattempt is allowed for the access category.

Another embodiment provides a user equipment (UE) performing accessbarring check in a wireless communication system. The UE may include: amemory; a transceiver; and a processor, connected to the memory and thetransceiver, that: controls the transceiver to receive a list of barringinformation, wherein each of the barring information includes a barringfactor and a barring time; controls the transceiver to receiveinformation on an access category related to barring informationincluded in the list; performs the access barring check for the accesscategory, based on the barring information related to the accesscategory; and performs uplink transmission, if an access attempt isallowed for the access category.

Signaling of a network for transmission of the barring information canbe decreased.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows LTE system architecture.

FIG. 2 shows a control plane of a radio interface protocol of an LTEsystem.

FIG. 3 shows a user plane of a radio interface protocol of an LTEsystem.

FIG. 4 shows 5G system architecture.

FIG. 5 shows functional split between NG-RAN and 5GC

FIG. 6 shows an example of access barring check.

FIG. 7 shows an example of access barring check for Application specificCongestion control for Data Communication (ACDC).

FIG. 8 shows an access control procedure based on access barringinformation mapped to an access category, according to an embodiment ofthe present invention.

FIG. 9 shows an example of a mapping relationship between at least oneaccess category and barring information, according to an embodiment ofthe present invention.

FIG. 10 shows an access control procedure based on access barringinformation mapped to an access category, according to an embodiment ofthe present invention.

FIG. 11 shows an example of network slice group, according to anembodiment of the present invention.

FIG. 12 shows an example of slice group based access barringconfiguration, according to an embodiment of the present invention.

FIG. 13 shows an example of common access barring configuration,according to an embodiment of the present invention.

FIG. 14 shows an access barring mechanism based on network slice group,according to an embodiment of the present invention.

FIG. 15 is a block diagram illustrating a method for a UE to performaccess barring check according to an embodiment of the presentinvention.

FIG. 16 is a block diagram illustrating a wireless communication systemaccording to the embodiment of the present invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The technology described below can be used in various wirelesscommunication systems such as code division multiple access (CDMA),frequency division multiple access (FDMA), time division multiple access(TDMA), orthogonal frequency division multiple access (OFDMA), singlecarrier frequency division multiple access (SC-FDMA), etc. The CDMA canbe implemented with a radio technology such as universal terrestrialradio access (UTRA) or CDMA-2000. The TDMA can be implemented with aradio technology such as global system for mobile communications(GSM)/general packet ratio service (GPRS)/enhanced data rate for GSMevolution (EDGE). The OFDMA can be implemented with a radio technologysuch as institute of electrical and electronics engineers (IEEE) 802.11(Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, evolved UTRA (E-UTRA), etc.IEEE 802.16m is evolved from IEEE 802.16e, and provides backwardcompatibility with a system based on the IEEE 802.16e. The UTRA is apart of a universal mobile telecommunication system (UMTS). 3rdgeneration partnership project (3GPP) long term evolution (LTE) is apart of an evolved UMTS (E-UMTS) using the E-UTRA. The 3GPP LTE uses theOFDMA in a downlink and uses the SC-FDMA in an uplink. LTE-advanced(LTE-A) is an evolution of the LTE. 5G communication system is anevolution of the LTE-A.

For clarity, the following description will focus on LTE-A/5G. However,technical features of the present invention are not limited thereto.

FIG. 1 shows LTE system architecture. The communication network iswidely deployed to provide a variety of communication services such asvoice over internet protocol (VoIP) through IMS and packet data.

Referring to FIG. 1, the LTE system architecture includes one or moreuser equipment (UE; 10), an evolved-UMTS terrestrial radio accessnetwork (E-UTRAN) and an evolved packet core (EPC). The UE 10 refers toa communication equipment carried by a user. The UE 10 may be fixed ormobile, and may be referred to as another terminology, such as a mobilestation (MS), a user terminal (UT), a subscriber station (SS), awireless device, etc.

The E-UTRAN includes one or more evolved node-B (eNB) 20, and aplurality of UEs may be located in one cell. The eNB 20 provides an endpoint of a control plane and a user plane to the UE 10. The eNB 20 isgenerally a fixed station that communicates with the UE 10 and may bereferred to as another terminology, such as a base station (BS), a basetransceiver system (BTS), an access point, etc. One eNB 20 may bedeployed per cell. There are one or more cells within the coverage ofthe eNB 20. A single cell is configured to have one of bandwidthsselected from 1.25, 2.5, 5, 10, and 20 MHz, etc., and provides downlinkor uplink transmission services to several UEs. In this case, differentcells can be configured to provide different bandwidths.

Hereinafter, a downlink (DL) denotes communication from the eNB 20 tothe UE 10, and an uplink (UL) denotes communication from the UE 10 tothe eNB 20. In the DL, a transmitter may be a part of the eNB 20, and areceiver may be a part of the UE 10. In the UL, the transmitter may be apart of the UE 10, and the receiver may be a part of the eNB 20.

The EPC includes a mobility management entity (MME) which is in chargeof control plane functions, and a system architecture evolution (SAE)gateway (S-GW) which is in charge of user plane functions. The MME/S-GW30 may be positioned at the end of the network and connected to anexternal network. The MME has UE access information or UE capabilityinformation, and such information may be primarily used in UE mobilitymanagement. The S-GW is a gateway of which an endpoint is an E-UTRAN.The MME/S-GW 30 provides an end point of a session and mobilitymanagement function for the UE 10. The EPC may further include a packetdata network (PDN) gateway (PDN-GW). The PDN-GW is a gateway of which anendpoint is a PDN.

The MME provides various functions including non-access stratum (NAS)signaling to eNBs 20, NAS signaling security, access stratum (AS)security control, Inter core network (CN) node signaling for mobilitybetween 3GPP access networks, idle mode UE reachability (includingcontrol and execution of paging retransmission), tracking area listmanagement (for UE in idle and active mode), P-GW and S-GW selection,MME selection for handovers with MME change, serving GPRS support node(SGSN) selection for handovers to 2G or 3G 3GPP access networks,roaming, authentication, bearer management functions including dedicatedbearer establishment, support for public warning system (PWS) (whichincludes earthquake and tsunami warning system (ETWS) and commercialmobile alert system (CMAS)) message transmission. The S-GW host providesassorted functions including per-user based packet filtering (by e.g.,deep packet inspection), lawful interception, UE Internet protocol (IP)address allocation, transport level packet marking in the DL, UL and DLservice level charging, gating and rate enforcement, DL rate enforcementbased on APN-AMBR. For clarity MME/S-GW 30 will be referred to hereinsimply as a “gateway,” but it is understood that this entity includesboth the MME and S-GW.

Interfaces for transmitting user traffic or control traffic may be used.The UE 10 and the eNB 20 are connected by means of a Uu interface. TheeNBs 20 are interconnected by means of an X2 interface. Neighboring eNBsmay have a meshed network structure that has the X2 interface. The eNBs20 are connected to the EPC by means of an S1 interface. The eNBs 20 areconnected to the MME by means of an S1-MME interface, and are connectedto the S-GW by means of S1-U interface. The S1 interface supports amany-to-many relation between the eNB 20 and the MME/S-GW.

The eNB 20 may perform functions of selection for gateway 30, routingtoward the gateway 30 during a radio resource control (RRC) activation,scheduling and transmitting of paging messages, scheduling andtransmitting of broadcast channel (BCH) information, dynamic allocationof resources to the UEs 10 in both UL and DL, configuration andprovisioning of eNB measurements, radio bearer control, radio admissioncontrol (RAC), and connection mobility control in LTE ACTIVE state. Inthe EPC, and as noted above, gateway 30 may perform functions of pagingorigination, LTE_IDLE state management, ciphering of the user plane, SAEbearer control, and ciphering and integrity protection of NAS signaling.

FIG. 2 shows a control plane of a radio interface protocol of an LTEsystem. FIG. 3 shows a user plane of a radio interface protocol of anLTE system.

Layers of a radio interface protocol between the UE and the E-UTRAN maybe classified into a first layer (L1), a second layer (L2), and a thirdlayer (L3) based on the lower three layers of the open systeminterconnection (OSI) model that is well-known in the communicationsystem. The radio interface protocol between the UE and the E-UTRAN maybe horizontally divided into a physical layer, a data link layer, and anetwork layer, and may be vertically divided into a control plane(C-plane) which is a protocol stack for control signal transmission anda user plane (U-plane) which is a protocol stack for data informationtransmission. The layers of the radio interface protocol exist in pairsat the UE and the E-UTRAN, and are in charge of data transmission of theUu interface.

A physical (PHY) layer belongs to the L1. The PHY layer provides ahigher layer with an information transfer service through a physicalchannel. The PHY layer is connected to a medium access control (MAC)layer, which is a higher layer of the PHY layer, through a transportchannel. A physical channel is mapped to the transport channel. Data istransferred between the MAC layer and the PHY layer through thetransport channel. Between different PHY layers, i.e., a PHY layer of atransmitter and a PHY layer of a receiver, data is transferred throughthe physical channel using radio resources. The physical channel ismodulated using an orthogonal frequency division multiplexing (OFDM)scheme, and utilizes time and frequency as a radio resource.

The PHY layer uses several physical control channels. A physicaldownlink control channel (PDCCH) reports to a UE about resourceallocation of a paging channel (PCH) and a downlink shared channel(DL-SCH), and hybrid automatic repeat request (HARQ) information relatedto the DL-SCH. The PDCCH may carry a UL grant for reporting to the UEabout resource allocation of UL transmission. A physical control formatindicator channel (PCFICH) reports the number of OFDM symbols used forPDCCHs to the UE, and is transmitted in every subframe. A physicalhybrid ARQ indicator channel (PHICH) carries an HARQ acknowledgement(ACK)/non-acknowledgement (NACK) signal in response to UL transmission.A physical uplink control channel (PUCCH) carries UL control informationsuch as HARQ ACK/NACK for DL transmission, scheduling request, and CQI.A physical uplink shared channel (PUSCH) carries a UL-uplink sharedchannel (SCH).

A physical channel consists of a plurality of subframes in time domainand a plurality of subcarriers in frequency domain. One subframeconsists of a plurality of symbols in the time domain. One subframeconsists of a plurality of resource blocks (RBs). One RB consists of aplurality of symbols and a plurality of subcarriers. In addition, eachsubframe may use specific subcarriers of specific symbols of acorresponding subframe for a PDCCH. For example, a first symbol of thesubframe may be used for the PDCCH. The PDCCH carries dynamic allocatedresources, such as a physical resource block (PRB) and modulation andcoding scheme (MCS). A transmission time interval (TTI) which is a unittime for data transmission may be equal to a length of one subframe. Thelength of one subframe may be 1 ms.

The transport channel is classified into a common transport channel anda dedicated transport channel according to whether the channel is sharedor not. A DL transport channel for transmitting data from the network tothe UE includes a broadcast channel (BCH) for transmitting systeminformation, a paging channel (PCH) for transmitting a paging message, aDL-SCH for transmitting user traffic or control signals, etc. The DL-SCHsupports HARQ, dynamic link adaptation by varying the modulation, codingand transmit power, and both dynamic and semi-static resourceallocation. The DL-SCH also may enable broadcast in the entire cell andthe use of beamforming. The system information carries one or moresystem information blocks. All system information blocks may betransmitted with the same periodicity. Traffic or control signals of amultimedia broadcast/multicast service (MBMS) may be transmitted throughthe DL-SCH or a multicast channel (MCH).

A UL transport channel for transmitting data from the UE to the networkincludes a random access channel (RACH) for transmitting an initialcontrol message, a UL-SCH for transmitting user traffic or controlsignals, etc. The UL-SCH supports HARQ and dynamic link adaptation byvarying the transmit power and potentially modulation and coding. TheUL-SCH also may enable the use of beamforming. The RACH is normally usedfor initial access to a cell.

A MAC layer belongs to the L2. The MAC layer provides services to aradio link control (RLC) layer, which is a higher layer of the MAClayer, via a logical channel. The MAC layer provides a function ofmapping multiple logical channels to multiple transport channels. TheMAC layer also provides a function of logical channel multiplexing bymapping multiple logical channels to a single transport channel. A MACsublayer provides data transfer services on logical channels.

The logical channels are classified into control channels fortransferring control plane information and traffic channels fortransferring user plane information, according to a type of transmittedinformation. That is, a set of logical channel types is defined fordifferent data transfer services offered by the MAC layer. The logicalchannels are located above the transport channel, and are mapped to thetransport channels.

The control channels are used for transfer of control plane informationonly. The control channels provided by the MAC layer include a broadcastcontrol channel (BCCH), a paging control channel (PCCH), a commoncontrol channel (CCCH), a multicast control channel (MCCH) and adedicated control channel (DCCH). The BCCH is a downlink channel forbroadcasting system control information. The PCCH is a downlink channelthat transfers paging information and is used when the network does notknow the location cell of a UE. The CCCH is used by UEs having no RRCconnection with the network. The MCCH is a point-to-multipoint downlinkchannel used for transmitting MBMS control information from the networkto a UE. The DCCH is a point-to-point bi-directional channel used by UEshaving an RRC connection that transmits dedicated control informationbetween a UE and the network.

Traffic channels are used for the transfer of user plane informationonly. The traffic channels provided by the MAC layer include a dedicatedtraffic channel (DTCH) and a multicast traffic channel (MTCH). The DTCHis a point-to-point channel, dedicated to one UE for the transfer ofuser information and can exist in both uplink and downlink. The MTCH isa point-to-multipoint downlink channel for transmitting traffic datafrom the network to the UE.

Uplink connections between logical channels and transport channelsinclude the DCCH that can be mapped to the UL-SCH, the DTCH that can bemapped to the UL-SCH and the CCCH that can be mapped to the UL-SCH.Downlink connections between logical channels and transport channelsinclude the BCCH that can be mapped to the BCH or DL-SCH, the PCCH thatcan be mapped to the PCH, the DCCH that can be mapped to the DL-SCH, andthe DTCH that can be mapped to the DL-SCH, the MCCH that can be mappedto the MCH, and the MTCH that can be mapped to the MCH.

An RLC layer belongs to the L2. The RLC layer provides a function ofadjusting a size of data, so as to be suitable for a lower layer totransmit the data, by concatenating and segmenting the data receivedfrom an upper layer in a radio section. In addition, to ensure a varietyof quality of service (QoS) required by a radio bearer (RB), the RLClayer provides three operation modes, i.e., a transparent mode (TM), anunacknowledged mode (UM), and an acknowledged mode (AM). The AM RLCprovides a retransmission function through an automatic repeat request(ARQ) for reliable data transmission. Meanwhile, a function of the RLClayer may be implemented with a functional block inside the MAC layer.In this case, the RLC layer may not exist.

A packet data convergence protocol (PDCP) layer belongs to the L2. ThePDCP layer provides a function of header compression function thatreduces unnecessary control information such that data being transmittedby employing IP packets, such as IPv4 or IPv6, can be efficientlytransmitted over a radio interface that has a relatively smallbandwidth. The header compression increases transmission efficiency inthe radio section by transmitting only necessary information in a headerof the data. In addition, the PDCP layer provides a function ofsecurity. The function of security includes ciphering which preventsinspection of third parties, and integrity protection which preventsdata manipulation of third parties.

A radio resource control (RRC) layer belongs to the L3. The RLC layer islocated at the lowest portion of the L3, and is only defined in thecontrol plane. The RRC layer takes a role of controlling a radioresource between the UE and the network. For this, the UE and thenetwork exchange an RRC message through the RRC layer. The RRC layercontrols logical channels, transport channels, and physical channels inrelation to the configuration, reconfiguration, and release of RBs. AnRB is a logical path provided by the L1 and L2 for data delivery betweenthe UE and the network. That is, the RB signifies a service provided theL2 for data transmission between the UE and E-UTRAN. The configurationof the RB implies a process for specifying a radio protocol layer andchannel properties to provide a particular service and for determiningrespective detailed parameters and operations. The RB is classified intotwo types, i.e., a signaling RB (SRB) and a data RB (DRB). The SRB isused as a path for transmitting an RRC message in the control plane. TheDRB is used as a path for transmitting user data in the user plane.

Referring to FIG. 2, the RLC and MAC layers (terminated in the eNB onthe network side) may perform functions such as scheduling, automaticrepeat request (ARQ), and hybrid automatic repeat request (HARQ). TheRRC layer (terminated in the eNB on the network side) may performfunctions such as broadcasting, paging, RRC connection management, RBcontrol, mobility functions, and UE measurement reporting andcontrolling. The NAS control protocol (terminated in the MME of gatewayon the network side) may perform functions such as a SAE bearermanagement, authentication, LTE_IDLE mobility handling, pagingorigination in LTE_IDLE, and security control for the signaling betweenthe gateway and UE.

Referring to FIG. 3, the RLC and MAC layers (terminated in the eNB onthe network side) may perform the same functions for the control plane.The PDCP layer (terminated in the eNB on the network side) may performthe user plane functions such as header compression, integrityprotection, and ciphering.

FIG. 4 shows 5G system architecture.

Referring to FIG. 4, a Next Generation Radio Access Network (NG-RAN)node may be either a gNB providing NR Radio Access (NR) user plane andcontrol plane protocol terminations towards the UE or an ng-eNBproviding Evolved Universal Terrestrial Radio Access (E-UTRA) user planeand control plane protocol terminations towards the UE. The gNBs andng-eNBs may be interconnected with each other by means of the Xninterface. The gNBs and ng-eNBs may be also connected by means of the NGinterfaces to the 5G Core Network (5GC), more specifically to the AMF(Access and Mobility Management Function) by means of the NG-C interfaceand to the UPF (User Plane Function) by means of the NG-U interface. TheNG-C may be control plane interface between NG-RAN and 5GC, and the NG-Umay be user plane interface between NG-RAN and 5GC.

FIG. 5 shows functional split between NG-RAN and 5GC

Referring to FIG. 5, the gNB and ng-eNB may host the followingfunctions:

-   -   Functions for Radio Resource Management: Radio Bearer Control,        Radio Admission Control, Connection Mobility Control, Dynamic        allocation of resources to UEs in both uplink and downlink        (scheduling);    -   IP header compression, encryption and integrity protection of        data;    -   Selection of an AMF at UE attachment when no routing to an AMF        can be determined from the information provided by the UE;    -   Routing of User Plane data towards UPF(s);    -   Routing of Control Plane information towards AMF;    -   Connection setup and release;    -   Scheduling and transmission of paging messages;    -   Scheduling and transmission of system broadcast information        (originated from the AMF or O&M);    -   Measurement and measurement reporting configuration for mobility        and scheduling;    -   Transport level packet marking in the uplink;    -   Session Management;    -   Support of Network Slicing;    -   QoS Flow management and mapping to data radio bearers;    -   Support of UEs in RRC_INACTIVE state;    -   Distribution function for NAS messages;    -   Radio access network sharing;    -   Dual Connectivity;    -   Tight interworking between NR and E-UTRA.

The Access and Mobility Management Function (AMF) may host the followingmain functions:

-   -   NAS signalling termination;    -   NAS signalling security;    -   AS Security control;    -   Inter CN node signalling for mobility between 3GPP access        networks;    -   Idle mode UE Reachability (including control and execution of        paging retransmission);    -   Registration Area management;    -   Support of intra-system and inter-system mobility;    -   Access Authentication;    -   Access Authorization including check of roaming rights;    -   Mobility management control (subscription and policies);    -   Support of Network Slicing;    -   SMF selection.

The User Plane Function (UPF) may host the following main functions:

-   -   Anchor point for Intra-/Inter-RAT mobility (when applicable);    -   External PDU session point of interconnect to Data Network;    -   Packet routing & forwarding;    -   Packet inspection and User plane part of Policy rule        enforcement;    -   Traffic usage reporting;    -   Uplink classifier to support routing traffic flows to a data        network;    -   Branching point to support multi-homed PDU session;    -   QoS handling for user plane, e.g. packet filtering, gating,        UL/DL rate enforcement;    -   Uplink Traffic verification (SDF to QoS flow mapping);    -   Downlink packet buffering and downlink data notification        triggering.

The Session Management function (SMF) may host the following mainfunctions:

-   -   Session Management;    -   UE IP address allocation and management;    -   Selection and control of UP function;    -   Configures traffic steering at UPF to route traffic to proper        destination;    -   Control part of policy enforcement and QoS;    -   Downlink Data Notification.

FIG. 6 shows an example of access barring check.

Referring to FIG. 6, in the overload or congest state of the network orthe base station, the base station may broadcast access class barring(ACB)-related information through system information. The systeminformation may be system information block (SIB) type 2.

The SIB type 1 may include ACB-related information like the followingtable.

TABLE 1 Field Description ac-BarringFactor When a random value generatedby the UE is smaller than a value of ac-BarringFactor, access isallowed. If not, the access is barred. ac-BarringForCSFB ACB for circuitswitch (CS) fallback. The CS fallback converts a VoLTE call to aprevious 3G call. ac-BarringForEmergency ACB for emergency serviceac-BarringForMO-Data ACB for mobile orienting dataac-BarringForMO-Signalling ACB for mobile orienting control signalac-BarringForSpecialAC ACB for specific access classes, that is, 11 to15. ac-BarringTime Represents time when the access is barred.ssac-BarringForMMTEL- ACB for each service for mobile Video orienting ofMMTEL video. ssac-BarringForMMTEL- ACB for each service for mobile Voiceorienting of MMTEL voice.

Meanwhile, UE1 may determine an IMS service, for example, mobileorienting of a call by VoLTE and generates a service request message.Similarly, UE2 may determine mobile orienting of general data andgenerate the service request message.

Sequentially, the UE1 may generate an RRC connection request message.Similarly, the UE2 may generate the RRC connection request message.

Meanwhile, the UE1 may perform access barring check (that is, whetherthe ACB is applied). Similarly, the UE2 may perform access barring check(that is, whether the ACB is applied).

If the ACB is not applied, the UE1 and the UE2 may transmit the RRCconnection request message, respectively. However, when the ACB isapplied, both the UE1 and the UE2 may not transmit the RRC connectionrequest message, respectively.

The access barring check will be described in detail as follows.Generally, at least one of 10 access classes (for example, AC0, AC1, . .. , and AC9) may be randomly allocated to the UE. Exceptionally, forurgent emergency access, AC10 is allocated. As such, the value of therandomly allocated access class may be stored in each USIM of the UE1and the UE2. Then, the UE1 and the UE2 may verify whether the accessbarring is applied, by using a barring factor included in the receivedACB-related information, based on the stored access class. The accessbarring check may be performed in each access stratum (AS) layer, thatis, an RRC layer of the UE1 and the UE2.

The access barring check will be described in more detail as follows.

The ac-BarringPerPLMN-List may be included in the SIB type 2 received byeach of the UE1 and the UE2, and in the case where AC-BarringPerPLMNentry matched with plmn-identityIndex corresponding to the PLMN selectedin an higher layer is included in the ac-BarringPerPLMN-List,AC-BarringPerPLMN entry matched with the plmn-identityIndexcorresponding to the PLMN selected by the higher layer is selected.

Next, when the UE1 and the UE2 perform the RRC connection request, theaccess barring check may be performed by using T303 as Tbarring andusing ac-BarringForMO-Data as a barring parameter.

When the barring is determined, each AS(RRC) layer of the UE1 and theUE2 may notify a failure of the RRC connection establishment to thehigher layer.

Subsequently, as such, when the access is barred, each AS(RRC) layer maydetermine whether a T302 timer or a Tbarring timer is running. If thetimer is not running, the T302 timer or the Tbarring timer may be run.

Meanwhile, while the T302 timer or a Tbarring timer is running, theAS(RRC) layer considers that all the access to the corresponding cell isbarred.

As described above, in the network overload and congest situation, thebase station may provide the ACB-related information to the UE. Then,the UE may check whether access to the cell is barred by using thebarring factor included in the received ACB information based on itsaccess class stored in the USIM. Through the access barring check,finally, an access attempt is not performed. That is, when the access tothe corresponding cell is barred through the access barring check, theUE does not attempt the access, and when the access to the correspondingcell is not barred, the UE attempts the access. The access barring checkis performed in the AS layer. Herein, the access attempt means that theAS(RRC) layer of the UE transmits the RRC connection request message tothe base station.

Meanwhile, the access barring check may perform general mobileoriginating (MO) services of the UE, for example, originating call,originating data, originating IMS voice, and originating IMS video. Thatis, the ACB may be applied to access of all application programs (but,except for a response to an emergency service or paging).

As a method of differentiating a normal mobile originating (MO) service,for example, originating call, originating data, originating IMS voice,and originating IMS video, it is proposed application specificcongestion control for data communication (ACDC).

FIG. 7 shows an example of access barring check for Application specificCongestion control for Data Communication (ACDC).

Referring to FIG. 7, firstly, a base station may provide ACDC barringinformation to a UE through SIB.

Meanwhile, when a specific application is executed in a UE and a datacommunication service is required by the specific application, anapplication layer for controlling execution of the specific applicationmay provide application attribute related information to an NAS layer.

Then, on the basis of the application attribute related informationreceived from the application layer, the NAS layer of the UE maydetermine an application category for the ACDC.

Subsequently, when starting a service request procedure for a serviceconnection (transmission of a service request message or transmission ofan extended service request message), the NAS layer of the UE maydeliver information regarding the application category to an AS layer(i.e., RRC layer).

Before performing the service request procedure of the NAS layer(transmission of the service request message or transmission of anextended service request message), on the basis of the applicationcategory and ACDC barring information received from the network, the ASlayer (e.g., RRC layer) of the UE may perform ACDC barring check andthus determines whether to allow or not allow the service requestprocedure.

If it is determined not to be barred but to be allowed as a result ofthe ACDC barring check, the AS layer (i.e., RRC layer) of the UE maytransmit an RRC connection request message to the base station.

As described above, a service request required by an applicationcurrently being executed in the UE through the ACDC may be allowed orbarred through differentiation.

Meanwhile, NG-RAN may support overload and access control functionalitysuch as RACH back off, RRC Connection Reject, RRC Connection Release andUE based access barring mechanisms. One unified access control frameworkmay be applied for NR. For each identified access attempt one AccessCategory and one or more Access Identities may be selected. NG-RAN maybroadcast barring control information associated with Access Categoriesand Access Identities and the UE may determine whether an identifiedaccess attempt is authorized or not, based on the broadcasted barringinformation and the selected Access Category and Access Identities. Inthe case of multiple core networks sharing the same NG-RAN, the NG-RANprovides broadcasted barring control information for each PLMNindividually. The unified access control framework may be applicable toall UE states. The UE states may include RRC_IDLE, RRC_INACTIVE orRRC_CONNECTED state. In RRC_IDLE, the UE NAS informs RRC of the accesscategory and the Connection Request includes some information to enablethe gNB to decide whether to reject the request.

Based on operator's policy, the 5G system shall be able to prevent UEsfrom accessing the network using relevant barring parameters that varydepending on Access Identity and Access Category. Access Identities areconfigured at the UE as listed in Table 2. Any number of these AccessIdentities may be barred at any one time.

TABLE 2 Access Identity number UE configuration 0 UE is not configuredwith any parameters from this table 1 (NOTE 1) UE is configured forMultimedia Priority Service (MPS). 2 (NOTE 2) UE is configured forMission Critical Service (MCS). 3-10 Reserved for future use 11 (NOTE 3)Access Class 11 is configured in the UE. 12 (NOTE 3) Access Class 12 isconfigured in the UE. 13 (NOTE 3) Access Class 13 is configured in theUE. 14 (NOTE 3) Access Class 14 is configured in the UE. 15 (NOTE 3)Access Class 15 is configured in the UE. NOTE 1: Access Identity 1 isused by UEs configured for MPS, in the PLMNs where the configuration isvalid. The PLMNs where the configuration is valid are HPLMN, PLMNsequivalent to HPLMN, visited PLMNs of the home country, and configuredvisited PLMNs outside the home country. NOTE 2: Access Identity 2 isused by UEs configured for MCS, in the PLMNs where the configuration isvalid. The PLMNs where the configuration is valid are HPLMN or PLMNsequivalent to HPLMN. NOTE 3: Access Identities 11 and 15 are valid inHome PLMN only if the EHPLMN list is not present or in any EHPLMN.Access Identities 12, 13 and 14 are valid in Home PLMN and visited PLMNsof home country only. For this purpose the home country is defined asthe country of the MCC part of the IMSI.

Access Categories are defined by the combination of conditions relatedto UE and the type of access attempt as listed in Table 3. AccessCategory 0 shall not be barred, irrespective of Access Identities. Thenetwork can control the amount of access attempts relating to AccessCategory 0 by controlling whether to send paging or not.

TABLE 3 Access Category number Conditions related to UE Type of accessattempt 0 All MO signalling resulting from paging 1 (NOTE 1) UE isconfigured for All except for Emergency delay tolerant service andsubject to access control for Access Category 1, which is judged basedon relation of UE's HPLMN and the selected PLMN. 2 All Emergency 3 Allexcept for the conditions MO signalling resulting in Access Category 1.from other than paging 4 All except for the conditions MMTEL voice (NOTE3) in Access Category 1. 5 All except for the conditions MMTEL video inAccess Category 1. 6 All except for the conditions SMS in AccessCategory 1. 7 All except for the conditions MO data that do not inAccess Category 1. belong to any other Access Categories (NOTE 4) 8-31Reserved standardized Access Categories 32-63 (NOTE 2) All Based onoperator classification NOTE 1: The barring parameter for AccessCategory 1 is accompanied with information that define whether AccessCategory applies to UEs within one of the following categories: a) UEsthat are configured for delay tolerant service; b) UEs that areconfigured for delay tolerant service and are neither in their HPLMN norin a PLMN that is equivalent to it; c) UEs that are configured for delaytolerant service and are neither in the PLMN listed as most preferredPLMN of the country where the UE is roaming in the operator-defined PLMNselector list on the SIM/USIM, nor in their HPLMN nor in a PLMN that isequivalent to their HPLMN. NOTE 2: When there are an Access Categorybased on operator classification and a standardized Access Category toboth of which an access attempt can be categorized, and the standardizedAccess Category is neither 0 nor 2, the UE applies the Access Categorybased on operator classification. When there are an Access Categorybased on operator classification and a standardized Access Category toboth of which an access attempt can be categorized, and the standardizedAccess Category is 0 or 2, the UE applies the standardized AccessCategory. NOTE 3: Includes Real-Time Text (RTT). NOTE 4: Includes IMSMessaging.

One or more Access Identities and only one Access Category are selectedand tested for an access attempt. The 5G network shall be able tobroadcast barring control information (i.e. a list of barring parametersassociated with an Access Identity and an Access Category) in one ormore areas of the RAN. The UE shall be able to determine whether or nota particular new access attempt is allowed based on barring parametersthat the UE receives from the broadcast barring control information andthe configuration in the UE. In the case of multiple core networkssharing the same RAN, the RAN shall be able to apply access control forthe different core networks individually. The unified access controlframework shall be applicable both to UEs accessing the 5G CN usingE-UTRA and to UEs accessing the 5G CN using NR.

Since access categories involve service type property, accessesbelonging to a particular service shall be processed with higherpriority than others. For example, accesses for emergency services shallhave higher priority than that of normal services, or accesses fornormal services may have higher priority than that of Internet of Things(IoT) data transmissions. Meanwhile, in the NR, 64 access categories aredefined, and access barring check may be applied to 63 accesscategories. If access barring parameters is defined for each of theaccess categories, signaling of a network for transmission of the accessbarring parameters may increase. Therefore, access barring checkmechanisms based on access barring information set need to be proposed.Hereinafter, a method for a UE to perform access barring check based onaccess barring information set and an apparatus supporting the sameaccording to an embodiment of the present invention are described indetail.

According to an embodiment of the present invention, one or more accesscategories can be mapped to a particular access priority, and then a UEmay perform access barring mechanisms based on the access priority. Inthe present invention, the access priority can be referred to aspriority, barring priority, access barring information, barringinformation, access barring configuration or barring configuration.

FIG. 8 shows an access control procedure based on access barringinformation mapped to an access category, according to an embodiment ofthe present invention.

Referring to FIG. 8, in step S810, the UE may receive a list of barringinformation from a network. The list of barring information may bereceived from a base station via system information. For example, thesystem information may be system information block 1 or 2. The barringinformation may include certain barring factor and certain barring time.Table 4 shows an example of the list of barring information.

TABLE 4 Barring Factor Barring Time barring information #0 p05 s16barring information #1 p20 s32 barring information #2 p55 s64 barringinformation #3 P85 s128

Referring to table 4, the list of barring information may includebarring information #0 to barring information #3, and each of thebarring information may include certain barring factor and certainbarring time.

Table 5 shows an example of the list of barring information. In table 5,the list of barring information may be referred to asBarringPerPriority.

TABLE 5 BarringPerPriority ::= SEQUENCE (SIZE (1..maxPriority)) OFBarringPerPriority BarringPerPriority ::= SEQUENCE {  barringPriority#1  AC-BarringConfig OPTIONAL, -- Need OP,  barringPriority#2  AC-BarringConfig OPTIONAL, -- Need OP,  }  OPTIONAL -- Need OP }AC-BarringConfig ::=  SEQUENCE {  ac-BarringFactor   ENUMERATED {p00,p05, p10, p15, p20, p25, p30, p40, p50,   p60, p70, p75, p80, p85, p90,p95},  ac-BarringTime   ENUMERATED {s4, s8, s16, s32, s64, s128, s256,s512},  ac-BarringForSpecialAC    BIT STRING (SIZE(5)) }

Referring to table 5, the BarringPerPriority may includebarringPriority#1 and barringPriority#2, and each of the barringPrioritymay include certain ac-BarringFactor and certain ac-BarringTime.

Table 6 shows another example of the list of barring information. Intable 6, the list of barring information may be referred to asUAC-BarringInfoSetList, and the barring information may be referred toas UAC-BarringInfoSet.

TABLE 6 UAC-BarringPerCatList ::= SEQUENCE (SIZE (1..maxAccessCat-1)) ofUAC- BarringPerCat UAC-BarringPerCat ::= SEQUENCE {   Access Category  INTEGER (1..maxAccessCat-1),   uac-barringInfoSetIndex    INTEGER (1..maxBarringInfoSet) } UAC-BarringInfoSetList ::= SEQUENCE(maxBarringInfoSet) OF UAC-BarringInfoSet UAC-BarringInfoSet ::=SEQUENCE {  uac-BarringFactor  ENUMERATED {p00, p05, p10, p15, p20, p25,p30, p40,  p50, p60, p70, p75, p80, p85, p90, p95},  uac-BarringTimeENUMERATED {s4, s8, s16, s32, s64, s128, s256, s512}, uac-BarringForAccessIdentity     BIT STRING (SIZE(7)) }

Referring to table 6, the UAC-BarringInfoSetList may include one or moreUAC-BarringInfoSet, and each of the UAC-BarringInfoSet may includeuac-BarringFactor and uac-BarringTime.

In step S820, the UE may receive mapping information between an accesscategory and certain barring information included in the list. Referringto table 6, the UAC-BarringPerCat may include the AccessCategory and theuac-barringInfoSetIndex, and the uac-barringInfoSetIndex is an index ofthe entry in field uac-BarringInfoSetList. For instance, value 1corresponds to the first entry in uac-BarringInfoSetList, value 2corresponds to the second entry in this list and so on. Namely, theuac-barringInfoSetIndex may indicate certain barring information mappedto the AccessCategory, among the list of barring information.

A mapping relationship between access categories and barring informationwill be described in detail with reference to FIG. 9.

FIG. 9 shows an example of a mapping relationship between at least oneaccess category and barring information, according to an embodiment ofthe present invention.

Referring to FIG. 9, the barring information #0 may be mapped to accesscategory #1, access category #2 and access category #3. The barringinformation #1 may be mapped to access category #4 and access category#5. The barring information #2 may be mapped to access category #6,access category #7 and access category #8. The barring information #3may be mapped to access category #9. That is, one barring informationmay be mapped to at least one access category.

Table 7 shows another example of a mapping relationship between at leastone access category and a priority (i.e. the barring information).

TABLE 7 Priority Access category 0 AC 1 ... ... ... Default All ACsexcept the ones configured for the other priorities P AC#N (e.g. Delaytolerant services)

Returning back to FIG. 8, in step S820, the network may provide the UEwith part of mapping relationship between at least one access categoryand barring information. The network may provide the UE with a certainaccess category, and further the network may inform the UE which barringinformation is mapped to the certain access category. For example, thenetwork may provide the UE with the access category #3 and indicationindicating barring information #0.

Alternatively, in step S820, the network may provide the UE with allmapping relationship between at least one access category and barringinformation.

In step S830, the UE may perform access barring check for certain accesscategory, based on the certain barring information mapped to the certainaccess category. For this, the UE may select the certain barringinformation corresponding to the certain access category, and thendetermine whether or not access to a cell is barred based on theselected certain barring information. The certain access category may betransmitted from a non-access stratum (NAS) layer of the UE to a radioresource control (RRC) layer of the UE. If the UE NAS transmits certainaccess category to the UE RRC, and if the UE RRC has certain barringinformation mapped to the certain access category, the UE RRC mayperform access barring check for the certain access category, based onthe certain barring information mapped to the certain access category.

In step S840, the UE may perform uplink transmission to the cell if anaccess attempt is allowed for the access category. Otherwise, the UE maystart a timer if the access attempt is barred for the access category.

According to an embodiment of the present invention, one or more accesscategories can be mapped to a particular barring information, and then aUE may perform access barring mechanisms based on the barringinformation mapped to at least one access category. Therefore, comparedto the case where access barring parameters is defined for each of theaccess categories, signaling of a network for transmission of the accessbarring parameters can be decreased.

FIG. 10 shows an access control procedure based on access barringinformation mapped to an access category, according to an embodiment ofthe present invention.

UEs may perform access barring check based on access priorities. Afterreceiving broadcast indication including access barring elements for apriority, the UE determines whether access to a cell is allowed or notbased on the priority based access barring information.

Referring to FIG. 10, in step S1010, the UE may receive a barringinformation element for each priority. The list of barring informationelements is received via system information. For example, the systeminformation may be SIB1 or SIB2. Then, the UE may select barringinformation for a priority corresponding to the particular accesscategory. The priority and access category are indicated by the NASlayer of the UE. Alternatively, the priority is informed by the network,and the access category is indicated by the NAS layer of the UE.

One or more access categories may compose an access priority asillustrated in FIG. 9. The priority definition may be pre-configured orinformed by the network. For example, the priority definition may beinformed during Registration. For initial registration, the UE may notknow the access priority unless the operator has provided pre-configuredaccess priority information, e.g. in universal integrated circuit card(UICC). The UE will receive access priority information upon receptionof Registration Accept. The UE NAS layer may maintain the informationand deliver to the UE RRC layer when it submits a request.

Referring to table 7, access priorities may be composed of standardizedpriorities and operator-configured priorities. Also, Default accesspriority may be defined for the access where any priority has not beenassigned. Default priority may not need to set as the lowest prioritybecause some accesses will be defined for delay tolerant services andthe priority should be the lowest.

In step S1020, the UE may determine whether or not access to a cell isbarred based on the selected barring information. For example, the UERRC layer may determine whether access to a cell is allowed or not basedon priority included in the NAS request and access barring informationbroadcasted from the network.

In step S1030, the UE may perform uplink transmission to the cell if anaccess attempt is allowed for the access category. Otherwise, the UE maystart a timer if the access attempt is barred for the access category.

Meanwhile, network slicing is supported in 5G for network functionsoptimizations. The network operator may deploy different network sliceinstances for different groups of services. Each PDU session can bededicated to a particular network slice. Based on this, the network canprovide differentiated services to customers. To support a particularservice, the network operator may need to assign several network slices.For example, normal IMS services may require around three PDU sessions,mapping to three network slices, as they use three EPS bearers in 4G;one for signaling transmissions, another for voice call, and the otherfor video call. In other words, three network slices will be assigned toIMS services. Therefore, for the network to precisely control trafficfrom a particular service, the control shall be applied to severalnetwork slices which are assigned to the service. In 5G system, accessbarring mechanisms will be performed based on access categories. Asaccess categories also involve service type in definition, networkslicing and access categories have a relationship between them. In otherwords, access barring can be performed based on network slices.

According to an embodiment of the present invention, the UE may performaccess barring check using network slice group based barringconfiguration. The barring configuration may be based on the mapping ofnetwork slice group and access categories. Each network slice group maymap to one or more access categories. The mapping may be either decidedby the UE itself or provided by the network operator.

The network slice group may be defined as illustrated in FIG. 11. One ormore network slices may compose a network slice group. Each slice groupmay be mapping to one or more access categories where an access barringfactor can be assigned to each access category. If the PLMN that the UEis registered to supports network slicing and the UE has pre-configuredslicing information, the UE may use the configured group information.Or, the information may be delivered via Registration Accept message.

During the initial registration, the UE may not know network slice groupinformation. The network will inform the group information when it sendsRegistration Accept to the UE. The group information may be maintainedin the UE NAS layer and delivered to the UE RRC layer when the UErequests connection establishment. The network slice group informationmay include Default Slice Group as presented in FIG. 12. When none ofslice group can be applied in the UE, the UE will use Default SliceGroup. The gNB may send access barring information based on the slicegroups. If even Default Slice Group is not available, the UE may performcommon barring check based on only access categories as presented inFIG. 13. Since network slicing is an optional feature, the UEsregistered to PLMNs which do not support network slicing, of course, mayperform common barring check.

FIG. 14 shows an access barring mechanism based on network slice group,according to an embodiment of the present invention.

Referring to FIG. 14, initial registration procedures include step S1400to S1420, and procedures after successful registration include stepS1430 to S1450.

In step S1400, the UE may receive access barring information viabroadcast indication (e.g. SystemInformationBlock1 or 2) from the gNB.If the PLMN defines Default Slice Group for access control, thebroadcast indication may include barring information for the group.Alternatively, fi the PLMN does not define Default Slice Group or notsupport network slicing, the broadcast indication may include commonaccess barring information. The broadcast indication message (e.g.SystemInformationBlock1 or 2) can provide barring information based onslice groups as table 8.

TABLE 8 SystemInformationBlockType2 ::= SEQUENCE { ac-BarringInfoSliceGroup#1  SEQUENCE {   ac-BarringForAccessCategory#1BOOLEAN,   ac-BarringForAccessCategory#2 AC-BarringConfig OPTIONAL, --Need OP  }  ac-BarringInfoSliceGroup#2  SEQUENCE {  ac-BarringForAccessCategory#5 AC-BarringConfig OPTIONAL, -- Need OP  } ac-BarringInfoDefaultSliceGroup   SEQUENCE {  ac-BarringForAccessCategory#3 AC-BarringConfig OPTIONAL, -- Need OP  ac-BarringForAccessCategory#4 AC-BarringConfig OPTIONAL, -- Need OP  }

When the UE requests Registration, the UE NAS layer may inform necessaryinformation for connection establishment to the UE RRC layer. If the UEhas pre-configured Default Slice Group, the UE NAS layer may inform ofthe slice, if available, and optionally access category information(e.g. sliceGroupId, accessCategoryId) to the UE RRC layer.Alternatively, if the UE has no slice information, the UE NAS layer mayinform of access category to the UE RRC layer.

The UE RRC layer may select barring information and determine whetheraccess to a cell is barred or not.

In step S1410, the UE may transmit Registration Request if not barred.

In step S1420, the UE may receive Registration Accept with Slice GroupInformation and update the group information for the registered PLMN.The Slice Group Information may include a slice group identifier (e.g.sliceGroupId) and the associated access category lists.

In step S1430, the UE may receive access barring information based onnetwork slice group via broadcast indication (e.g.SystemInformationBlock1 or 2). The broadcast indication message (e.g.SystemInformationBlock1 or 2) can provide barring information based onslice groups as table 8. Then, the UE may update access barringinformation for the PLMN. During RRC connection establishment, the UERRC layer may select barring information for the network slice groupcorresponding to the particular access category.

Then, in step S1440, the UE may determine whether access to a cell isbarred or not.

In step S1450, the UE sends RRC connection request to the network if anaccess attempt is allowed for the access category. Otherwise, the UE maystart a timer if the access attempt is barred for the access category.

According to an embodiment of the present invention, the UE may receivea barring information element for each network slice group. The list ofbarring information elements is received via system information. Then,the UE may select barring information for a network slice groupcorresponding to the particular access category. The slice group may beindicated by the NAS layer of the UE. Then, the UE may determine whetheror not access to a cell is barred based on the selected barringinformation.

FIG. 15 is a block diagram illustrating a method for a UE to performaccess barring check according to an embodiment of the presentinvention.

Referring to FIG. 15, in step S1510, the UE may receive a list ofbarring information. Each of the barring information may include certainbarring factor and certain barring time.

The list of barring information may be received from a network. The listof barring information may be received via system information.

In step S1520, the UE may receive information on an access categoryrelated to certain barring information included in the list. Forinstance, the information may be mapping information between the accesscategory and the certain barring information included in the list. Thecertain barring information included in the list may be related to oneor more access categories. The mapping information may be received froma network.

In step S1530, the UE may perform the access barring check for theaccess category, based on the certain barring information related to theaccess category.

The access barring check for the access category may be performed basedon the certain barring information related to the access category, ifthe access category is included in the one or more access categories.

The access category may be transmitted from a non-access stratum (NAS)layer of the UE to a radio resource control (RRC) layer of the UE. Theaccess barring check for the access category may be performed based onthe certain barring information related to the access category, if theaccess category is transmitted from the NAS layer of the UE to the RRClayer of the UE.

In step S1540, the UE may perform uplink transmission, if an accessattempt is allowed for the access category. The uplink transmissionincludes transmission of a radio resource control (RRC) connectionrequest message. Alternatively, the UE may start a timer for the accesscategory, if the access attempt is barred for the access category.

According to an embodiment of the present invention, one or more accesscategories can be mapped to a particular barring information, and then aUE may perform access barring mechanisms based on the barringinformation mapped to at least one access category. Therefore, comparedto the case where barring information is defined for each of the accesscategories, signaling of a network for transmission of the barringinformation can be decreased.

FIG. 16 is a block diagram illustrating a wireless communication systemaccording to the embodiment of the present invention.

ABS 1600 includes a processor 1601, a memory 1602 and a transceiver1603. The memory 1602 is connected to the processor 1601, and storesvarious information for driving the processor 1601. The transceiver 1603is connected to the processor 1601, and transmits and/or receives radiosignals. The processor 1601 implements proposed functions, processesand/or methods. In the above embodiment, an operation of the basestation may be implemented by the processor 1601.

A UE 1610 includes a processor 1611, a memory 1612 and a transceiver1613. The memory 1612 is connected to the processor 1611, and storesvarious information for driving the processor 1611. The transceiver 1613is connected to the processor 1611, and transmits and/or receives radiosignals. The processor 1611 implements proposed functions, processesand/or methods. In the above embodiment, an operation of the userequipment may be implemented by the processor 1611.

The processor may include an application-specific integrated circuit(ASIC), a separate chipset, a logic circuit, and/or a data processingunit. The memory may include a read-only memory (ROM), a random accessmemory (RAM), a flash memory, a memory card, a storage medium, and/orother equivalent storage devices. The transceiver may include abase-band circuit for processing a wireless signal. When the embodimentis implemented in software, the aforementioned methods can beimplemented with a module (i.e., process, function, etc.) for performingthe aforementioned functions. The module may be stored in the memory andmay be performed by the processor. The memory may be located inside oroutside the processor, and may be coupled to the processor by usingvarious well-known means.

Various methods based on the present specification have been describedby referring to drawings and reference numerals given in the drawings onthe basis of the aforementioned examples. Although each method describesmultiple steps or blocks in a specific order for convenience ofexplanation, the invention disclosed in the claims is not limited to theorder of the steps or blocks, and each step or block can be implementedin a different order, or can be performed simultaneously with othersteps or blocks. In addition, those ordinarily skilled in the art canknow that the invention is not limited to each of the steps or blocks,and at least one different step can be added or deleted withoutdeparting from the scope and spirit of the invention.

The aforementioned embodiment includes various examples. It should benoted that those ordinarily skilled in the art know that all possiblecombinations of examples cannot be explained, and also know that variouscombinations can be derived from the technique of the presentspecification. Therefore, the protection scope of the invention shouldbe determined by combining various examples described in the detailedexplanation, without departing from the scope of the following claims.

What is claimed is:
 1. A method of performing, by a user equipment (UE),wireless communication, the method comprising: receiving, from anetwork, a first list including at least one index; receiving, from thenetwork, a second list including at least one barring information,wherein each of the at least one barring information is indexed by eachof the at least one index, and wherein each of the at least one barringinformation includes a barring factor and a barring time; based on anaccess attempt related to a first access category, selecting, among theat least one index from the first list, a first index that is related tothe first access category; after selecting the first index that isrelated to the first access category, selecting, among the at least onebarring information from the second list, first barring information thatis related to the first index related to the first access category;performing an access barring check for the first access category, basedon a first barring factor and a first barring time included in the firstbarring information; and performing uplink transmission based onperforming the access barring check.
 2. The method of claim 1, furthercomprising: determining the first access category for the access attemptto a cell.
 3. The method of claim 2, wherein the first access categoryis determined by a non-access stratum (NAS) layer of the UE, and thefirst access category is informed by the NAS layer of the UE to a radioresource control (RRC) layer of the UE.
 4. The method of claim 3,wherein, based on the first access category that the NAS layer of the UEinforms to the RRC layer of the UE, the first index that is related tothe first access category is selected, by the RRC layer of the UE, amongthe at least one index from the first list.
 5. The method of claim 1,wherein the second list is received from the network by via systeminformation.
 6. The method of claim 1, wherein the access barring checkfor the first access category is performed based on whether the firstaccess category is included in one or more access categories.
 7. Themethod of claim 1, wherein performing the access barring check for thefirst access category comprises: determining whether a random valuebetween 0 and 1 is less than the first barring factor included in thefirst barring information.
 8. The method of claim 1, further comprising:based on the access barring check indicating that the access attempt forthe first access category is barred, waiting an amount of time relatedto the first barring time included in the first barring informationbefore a new access attempt is performed for the first access category.9. The method of claim 1, further comprising: starting a timer for thefirst access category based on the access barring check indicating thatthe access attempt is barred for the first access category.
 10. Themethod of claim 1, wherein a plurality of access categories in the firstlist is configured to be a subset of a total number of accesscategories.
 11. The method of claim 1, wherein the uplink transmissionincludes transmission of a radio resource control (RRC) connectionrequest message.
 12. A user equipment (UE) configured to performwireless communication, the UE comprising: a transceiver; at least oneprocessor; and at least one computer memory operably connectable to theat least one processor and storing instructions that, when executed,cause the at least one processor to perform operations comprising:receiving, from a network through the transceiver, a first listincluding at least one index; receiving, from the network through thetransceiver, a second list including at least one barring information,wherein each of the at least one barring information is indexed by eachof the at least one index, and wherein each of the at least one barringinformation includes a barring factor and a barring time; based on anaccess attempt related to a first access category, selecting, among theat least one index from the first list, a first index that is related tothe first access category; after selecting the first index that isrelated to the first access category, selecting, among the at least onebarring information from the second list, first barring information thatis related to the first index related to the first access category;performing an access barring check for the first access category, basedon a first barring factor and a first barring time included in the firstbarring information; and performing uplink transmission, through thetransceiver, based on performing the access barring check.
 13. The UE ofclaim 12, wherein the first access category for the access attempt to acell is determined by the UE.
 14. The UE of claim 13, wherein the firstaccess category is determined by a non-access stratum (NAS) layer of theUE, and the first access category is informed by the NAS layer of the UEto a radio resource control (RRC) layer of the UE.
 15. The UE of claim14, wherein, based on the first access category that the NAS layer ofthe UE informs to the RRC layer of the UE, the first index that isrelated to the first access category is selected, by the RRC layer ofthe UE, among the at least one index from the first list.
 16. The UE ofclaim 12, wherein the second list is received from the network by viasystem information.
 17. The UE of claim 12, wherein the access barringcheck for the first access category is performed based on whether thefirst access category is included in one or more access categories. 18.The UE of claim 12, wherein performing the access barring check for thefirst access category comprises: determining whether a random valuebetween 0 and 1 is less than the first barring factor included in thefirst barring information.
 19. The UE of claim 12, wherein a pluralityof access categories in the first list is configured to be a subset of atotal number of access categories.
 20. An apparatus configured tocontrol a user equipment (UE), the apparatus comprising: one or moreprocessors; and one or more memories operably connected to the one ormore processors and storing instructions, wherein the one or moreprocessors execute the instructions to: receive, from a network, a firstlist including at least one index; receive, from the network, a secondlist including at least one barring information, wherein each of the atleast one barring information is indexed by each of the at least oneindex, and wherein each of the at least one barring information includesa barring factor and a barring time; based on an access attempt relatedto a first access category, select, among the at least one index fromthe first list, a first index that is related to the first accesscategory; after selecting the first index that is related to the firstaccess category, select, among the at least one barring information fromthe second list, first barring information that is related to the firstindex related to the first access category; perform an access barringcheck for the first access category, based on a first barring factor anda first barring time included in the first barring information; andperform uplink transmission based on performing the access barringcheck.